J.C. Tretter Free Agency: Re-sign the oft-injured center?

Green Bay Packers quarterback Aaron Rodgers (12) prepares to the snap as tackle Don Barclay (67), outside linebacker Andy Mulumba (55), tackle J.C. Tretter (73) and running back James Starks (44) line up at the line of scrimmage during an NFL football game against the Detroit Lions at Ford Field. The Packers defeated the Lions 27-23. Kirby Lee-USA TODAY Sports

Tretter hasn’t seen action since suffering a knee sprain in Week Seven but was never placed on IR. He’s been listed as a full participant in practice and “questionable” before multiple games, suggesting staff thought he was close to returning.

The surgery suggests either a new setback or a misdiagnosis of the original injury.

J.C. Tretter: Back-up money or starter?

The Green Bay offensive line has been elite, and it’s easy to forget Tretter was the starting center the first half of the season as the line’s performance was a bright spot for the team during a shaky start.

The Packers’ faith in his potential looked to be rewarded this season as he took the starting center job from Corey Linsley.

Head coach Mike McCarthy had also planned to make him the starting center back in 2014 before his second major injury in as many years.

The Cornell graduate missed the 2013 and 2014 season with ankle and knee injuries and worked hard to prove himself in 2015.

He appeared in all 16 games and was valued for his versatility, spending time as a back-up center, left tackle, and special teams blocker.

The Packers are better when he’s healthy.

But after a strong start to 2016, injury struck again, and after four years in the league he’s missed two and a half seasons to injury and has only started 10 games.

During that time, left tackle David Bakhtiari, another Ted Thompson fourth-round steal from 2013, has started 62.

The Packers’ staff have complimented Tretter on his work ethic while recovering from each injury as well as his attitude in accepting any Band-Aid offensive line role. It must be difficult for the young lineman to miss out while the team has delivered such a magical season.

He now enters the off-season with an existing injury and the Packers probably won’t get a chance to test his recovery on the field.

His health makes him too unreliable to bring back for starter money.

Part of the logic in letting Josh Sitton leave was the looming 2017 free agency of linemen David Bakhtiari, T.J. Lang and Tretter.

Bakhtiari was extended in September.

Lang probably got more expensive as he delivered his first Pro Bowl year.